Rails Tests Fail With Sqlite3

I seem to be getting a strange error when I run my tests in rails, they are all failing for the same reason and none of the online documentation seems particularly helpful in regards to this particular error:

SQLite3::SQLException: cannot rollback - no transaction is active

This error is crippling my ability to test my application and seems to have appeared suddenly. I have the latest version of sqlite3 (3.6.2), the latest sqlite3-ruby (1.2.4) gem and the latest rails (2.1.1).